Trying to refund after an item not delivered but how?

My buyer did not receive the item and started up a query in the resolution centre.

I am happy to refund the item and p&p in full. Just can't for the life of me find out on ebay how to do that!

Is a refund different in the resolution centre. Does ebay pay it and take it out of my account? Do I refund them direct? I want to refund as quickly as possible but cannot fathom out how to. Please help.